Till recently, respiratory diseases in rabbits have
been connected to the presence of the bacterium Pasteurella multocida, therefore the disease was called Pasteurellosis. This diagnosis is definitively outdated,
after cultures of samples taken from diseased rabbits revealed the presence
of a variety of bacteria: Bordetella bronchiseptica,
Staphylococcus sp., Pseudomonas sp., Chlamydia sp., Acinetobacter
sp., Moraxella catarrhalis, Mycoplasma sp.,
etc.

Non-bacterial causes can also lead to respiratory
diseases in rabbits:

Since the rabbit appears relaxed (rabbits often sleep with open eyes), the nostrils are closed, it may relate to physical obstruction of air through the throat or nose (stertor). Is the soft palate weak and floppy, or elongated, as has been observed in some older animals ?

∑lower respiratory
tract disease, which is characterized by anorexia, depression, dyspnea (abnormal or
difficult breathing) and cyanosis (blue discoloration of tongue, lips, gums,
due to shortage of oxygen), fever or hypothermia. Lower respiratory tract
disease can remain undetected for a long time, till the disease develops in
an acute form, with difficult respiration and sometimes coughing. When
respiration is difficult, it can be accompanied by bilateral bulging of the
eyes and excessive appearance of the nictitating eyelid (also called third
eyelid).

Rabbit with
severe respiratory distress and mouth breathing as well as conjunctivitis.
X-ray (below) show atelectasis of the lung. Since the rabbit has lost weight and
respiration was increasingly difficult, it was humanely pts. Necropsy
confirmed the presence of atelectatic spots of varying extent in one lung.

MediRabbit

Clinical examination

The following
points should be checked, when a respiratory disease is suspected:

1.Checking the rate of respiration
of the rabbit (30 to 60/min). Higher is normal, lower is abnormal.

2.Checking carefully the nostrils for discharge. This is
not always obvious, as rabbits are big groomers and will clean themselves
restlessly. Sometimes matted fur can be found on the front paw, sign that a
discharge has occurred.

3.Examining the eyes for conjunctivitis and dacryocystitis (excretion of purulent exudate or
lachrymal overflow).

4.Checking the face, the facial bones, to discover
irregularities, presence of abscess, swellings.

5.Rhinoscopy.

6.Taking deep nasal and tracheal samples in
order to do a bacterial culture; for the nostrils, it should be done on both
sides as the infection can be unilateral. The nostril swab can be done with a
flexible-wire calcium alginate tipped swab, 1 to 4 cm into the nostrils or
the nasopharyngeal region. An alternative methodis a nasal aspiration.

Nasal swab (bottom) and holder(top)

Kliniek voor
Pluimvee en Bijzondere Dieren, Universiteit Gent

Septicemia causes by the
bacterium Pasteurella multocida

7.Examining the
ears for infection. X-ray pictures of the skull may show the presence of an
increased opacity in the middle and external ear. Ear infection is often
associated to respiratory infection, via the passage of bacteria through the
Eustachian tube, but it is not an obligation. Often, the rabbit has a
decreased appetite, due to pain.

8.Microscopical examination of the blood and CBC
in order to reveal hematological changes like neutrophilia
(increased level of neutrophils), or leucopenia (decrease in the amount of
white blood cells in the blood). It
mayfurthermore help detect secondary organ failure.

9.When a heart problem is suspected, X-rays and
electrocardiography will help to detect cardiomegaly (enlargement of the
heart).

10.X-rays of the thorax will further help
detect the presence of a bacterial infection (increased opacity), bronchitis,
the presence of masses (abscess or neoplasia), or
edema (accumulation of an abnormally large amount of fluid) around the
lung(s) or the heart.

Infectious bacteria

Pasteurella multocidais quite
contagious, although some rabbits seem to show a higher resistance to the
bacterium than others. If Pasteurella sp.
is present, treatment must be started ASAP, be aggressive and long, at least two
weeks after total disappearance of the symptoms. It happens that a rabbit
never fully recovers and need to be on maintenance antibiotics for the rest
of its life.

Pasteurella sp. is
responsible for more than one difficult to treat disease in rabbits, to name
a few:

-pleuritis (inflammation of the tissue
around the lungs);

-pneumonia;

-pericarditis (inflammation of the
lining around the heart);

-otitis media or interna (middle or inner ear infection);

-dacryocystitis (infection
of the tear duct),

-conjunctivitis;,

-subcutaneous abscesses;

-mastitis (infection
of the milk glands).

The clinical
signs are multiple, including sneezing and coughing, and nasal discharge.

Kim Chilson

Sneezing
rabbit

This stage can evolve into lower respiratory tract
disease, with pleuro-pneumonia or pericarditis.

Bordetellabronchiseptica
is typically a bacterium that shows up, when a rabbit and a guinea pig are housed
together. It may be present asymptomatically in the nasal cavity of the
rabbit, without development of the disease. Its presence may increase the
susceptibility of the rabbit to Pasteurella sp. and the chances of
developing an infection, including bronchopneumonia. The bacterium is fatal
for the guinea pig.

Acinetobacter sp. is a
bacterium that has usually a low potential of virulence and thus rarely leads
to the development of pneumonia. Its presence tends to indicate that an
animal is colonized by this bacterium, rather than infected. Since it is
colonizing mainly, it is important to determine if Acinetobacter
sp. is the causative agent, or merely masking the presence of another
pathogen.

†

Michel
Gruaz

MediRabbit

Jonathan Cracknell
BVMS CertVACertZooMed
MRCVS

wildlife1.wildlifeinformation.org/S/00dis/Miscellaneous/

Img_ExophthalmosRabbit/JCRabbit_retrobulbar_mass02.htm

Further typical clinical signs related to a Pasteurellasp infection: head-tilt (top) caused by middle or
inner ear infection, which should be differentiate from encephalitozoonosis;
conjunctivitis (bottom left); and unilateral eye bulging caused by the
presence of a retrobulbar abscess (bottom right).

Treatment

Respiratory
tract diseases must be differentiated from a viral disease, a mechanical or neoplastic
obstruction or hypersensitivity. If nothing is found and the presence of
bacteria can be ruled out, the affected rabbit can be given antihistamines or
corticosteroids (no longer than 3 to 5 days).†

Successful treatment of upper respiratory infection
needs to be aggressive and long. Often a combination of antibiotics is used,
like oral administration of enrofloxacin or ciprofloxacin, accompanied by
gentamycin based nose drops.

Trimethoprim sulfadiazine is a bactericidal
antibiotic used in GI tract, respiratory and urinary infections, among
others. It is efficacious against a range of bacteria that affect rabbits,
including Pasteurella sp., Clostridia spp., Staphylococcus
sp., Bordetella sp., etc. It can be used long term, low dose. This
antibiotic often shows poor results in rabbits, and often the disease comes
back worse once the treatment is stopped. This could relate to the fact that
half-life of trimethoprim in a rabbit last only 40 min.

Azythromycin, a modified erythromycin,
that does not show the side effects of the later in rabbits, is very
efficacious in the treatment of Bordetella sp. (and so is
enrofloxacin). The azythromycin doses used for
rabbits (50mg/kg PO QD (SID) is much higher than that used for other small
animals like cats and dogs (5-8mg/kg). Treatment lasts generally 7 days,
after which an evaluation is done and eventual prolongation decided.

Cephalosporins are
bactericidal broad-spectrum antibiotics used to treat skeletal,
genital/urinary, skin and soft tissue bacterial and respiratory (associated
with Pasteurella sp.) infections, among others. There are several
generations of cephalosporin, each aiming a more or less specific group of
bacteria. Although quite safe when used in injected form, this drug is
potentially nephrotoxic.

The therapy against Pseudomonas sp., one of
the most difficult to treat infections, must be aggressive. A sensitivity
test must be done, as this bacterium is known to be multiresistant
to many antibiotics. Most successful treatments involve a combination of
antibiotics, for example:

∑Nebulization with a saline solution, mucolytics and antibiotics help bring the medication deep
in the bronchia and lungs in cases of rhinitis, sinusitis or pneumonia;

∑Fluid therapy and assisted force-feeding, when the
rabbit refuses to drink and eat.

If the respiratory disease is accompanied by
conjunctivitis and/or dacryocystitis, local
antibiotic therapy (e.g. enrofloxacin, gentamycin) must accompany the
treatment protocol.

A.
van Praag

Flora hold above a bowl of hot water to allow her
to breath humid air.

Video's about nebulization

Using a
nebulizer in a rabbit affected by upper respiratory infection (URI).

Nebulizing
"chamber", when the rabbit does not like to have a mask, is
panicking or aggressive.

A big thank
you to Debbie Hanson. Without her help, time and expertise, the making of
the nebulizer video would not have been possible. Thanks also very much to
Rachel Ihlenfeldt and her rabbit Bunbun for the demonstrations.

Remerciements

Many thanks to Michel Gruaz (Switzerland), to Kim Chilson
(USA), to Tal Saarony (USA) and to DrKatleenHermans,
(KliniekvoorPluimvee en BijzondereDieren, Universiteit Gent, BelgiŽ) for the permission to use their pictures to
illustrate this article.